ACIDS, BASES, NEUTRAL SUBSTANCES 1Q7 



It reverses the color change produced by acids. 

 Bases turn red litmus paper blue. 



Neutralization. If the right amount of hydrochloric 

 acid is mixed with the right amount of sodium hy- 

 droxide, a base, all properties of both the acid and the 

 base disappear. The resulting substance does not 

 have a sour taste, or a soapy feeling, and it does 

 not have any action at all on litmus paper. The acid 

 has neutralized the base, and the base has neutralized 

 the acid. All the distinguishing acid and basic prop- 

 erties have gone. If the solution of the acid and the 

 base is evaporated a white powder remains. If this 

 is tasted, it will be found to be common table salt. The 

 liquid evaporated was water. When an acid is added 

 to a base, the product formed is a salt and water. 

 This may be written in the form of the equation: 



acid + base = salt + water. 



This action of an acid 011 a base is called neutralization. 

 Salts. The products of neutralization are a salt and 

 water. Salts as a class have no particular taste. They 

 have no action at all on red or blue litmus paper and 

 hence are known as neutral substances. Not all neutral 

 substances are salts, however. For example : water, 

 alcohol, and milk are neutral substances, but they are 

 not salts. 



Acid 4- Base = Salt + Water. 

 H Cl + NaOH = Na Cl + H 2 O. 

 H N0 3 -f NaOH Na NO 3 -f H 2 O. 

 H,SO 4 -f- 2NaOH = Na.,SO 4 + 2H,0. 



